| 西宁近郊大气氮干湿沉降研究 |
| 摘要点击 3416 全文点击 1053 投稿时间：2016-09-28 修订日期：2016-11-11 |
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| 中文关键词 大气活性氮 干沉降 湿沉降 城郊地区 青藏高原 |
| 英文关键词 atmospheric reactive N dry deposition wet deposition suburban area Tibetan Plateau |
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| 中文摘要 |
| 本研究在青海省西宁市城郊二十里铺莫家泉湾气象站开展了完整的2年（2014和2015年）大气无机氮干沉降和混合沉降（湿沉降加部分干沉降）监测.干沉降估算通过被动采样器采集的NH3和NO2浓度和Geos-Chem全球化学模式模拟的气体干沉降速率相乘获得；混合沉降的测定采用雨量器.结果表明，气态NH3和NO2年均浓度分别为8.8 μg·m-3和19.6 μg·m-3，且2015年NH3月均浓度显著高于2014年.NH3浓度的季节变化呈现春夏高、秋冬低的特征，而NO2浓度季节变化幅度较小.降水中NH4+-N和NO3--N年均浓度为2.2 mg·L-1和1.8 mg·L-1，秋季降水NH4+-N浓度比其他季节低55%，而NO3--N浓度在秋冬季比春夏季高约26%.气态NH3和NO2的干沉降量分别为9.0 kg·（hm2·a）-1和2.8 kg·（hm2·a）-1，降水中NH4+-N和NO3--N的混合沉降量分别为7.6 kg·（hm2·a）-1和6.2 kg·（hm2·a）-1.还原态氮（NH3和NH4+-N）在氮沉降中占主导地位.大气氮素总沉降（干沉降加混合沉降）量为25.6 kg·（hm2·a）-1，为城郊农田提供重要的环境养分；但这一氮素输入量超过了陆地生态系统氮沉降临界负荷[10~20 kg·（hm2·a）-1]，意味着研究区周边林地（如北山）和水体生态系统面临"氮饱和"的环境风险. |
| 英文摘要 |
| This study conducted a full two-year (2014 and 2015) measurements of dry and bulk deposition of atmospheric inorganic nitrogen (N) at the suburb of Xining city, Qinghai province. Dry N deposition fluxes were calculated by multiplying the atmospheric concentrations of NH3 and NO2 measured using passive samplers with the modeled dry deposition velocities provided by the GEOS-Chem global chemical transport model, while bulk N deposition fluxes were measured using precipitation gauge. Annual mean concentrations of gaseous NH3 and NO2 averaged 8.8 and 19.6 μg·m-3, respectively, with significantly higher values in 2015 than in 2014. Seasonal mean NH3 concentrations were higher in spring and summer than in autumn and winter, but the concentrations of NO2 changed little from season to season, with a small peak in autumn. Annual mean concentrations of NH4+-N and NO3--N in precipitation averaged 2.2 and 1.8 mg·L-1, respectively. Concentrations of NH4+-N in autumn were~55% lower than those in other seasons, whereas those of NO3--N in autumn or winter were~26% higher than those in spring and summer. Dry deposition of NH3 and NO2 was 9.0 and 2.8 kg·(hm2·a)-1, respectively. Bulk deposition of NH4+-N and NO3--N in precipitation was 7.6 and 6.2 kg·(hm2·a)-1, respectively. Reduced N (gaseous NH3 and NH4+-N in precipitation) was the dominant form of N deposition. The total dry and wet N deposition was 25.6 kg·(hm2·a)-1, which represented significant nutrient input from the environment to the suburban farmland, but this amount of deposited N exceeded the critical loads[10-20 kg·(hm2·a)-1] of terrestrial ecosystems, suggesting a risk of "N saturation" in the local natural environment. |
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